Type I or Insulin-Dependent Diabetes Mellitus (IDDM) arises in genetically predisposed individuals as a consequence of immune mediated destruction of the pancreatic islet insulin secreting '-cells. The onset of clinical symptoms of diabetes represents the end point of a chronic progressive decline in '-cell function, and it appears only when the majority of '-cells have been lost. Since IDDM develops insidiously, often years after the induction of the pathogenic immune-mediated destructive process, it can be predicted using immunological markers and tests of insulin secretion. The Diabetes Prevention Trial of Type-I Diabetes (DPT-I) has been designed to test whether intervention during the prodromal period of the disease can delay its clinical onset. The major objective of the DPT-I is to determine whether early intervention by antigen based therapies in non-diabetic relatives of persons with IDDM can delay their development of IDDM as a clinical disease. UAB will be participating in the recruitment, screening and staging components of the protocol.